In many applications, it is necessary to seal a casing, for example an engine casing, such that fluids do not leak out of the casing. It may also be desirable to prevent contaminants, such as water and dirt, from getting inside the casing.
There are many ways in which a casing may be sealed, but it is common to use a “formed-in-place” sealant such as RTV to help seal between appropriate sealing surfaces of different portions of the casing.
One of the difficulties in sealing an engine casing is that the different portions of the engine casing may be made from different materials, and may therefore expand by different amounts during operation of the engine owing to differing coefficients of thermal expansion. As a result of the differing amounts of expansion, the sealant may become de-bonded from one of the sealing surfaces, which allows engine oil to leak from the casing.
It is known to clean one or more of the sealing surfaces using a cleaning fluid before applying the sealant and assembling the engine casing. However, such measures may not be sufficient to prevent the sealant from de-bonding during operation of the engine.